This invention relates to three-way valves which maintain a completely closed system to perform regular irrigation and to collect urine specimens for urinalysis.
Two major varieties of catheters are available which are selected according to the use for which they are intended. Simple non-retention catheters are suitable for short term insertion in order to obtain specimens or to relieve acute bladder distention. Self-retaining catheters, to which the present invention relates, are designed to be left in place for long term drainage. The Foley balloon catheter is the most common form of self-retaining device. A modification of the Foley is the three-way catheter, which incorporates an additional lumen for the purpose of irrigating the bladder.
Infection stands as the most common and potentially dangerous result of urethral catherization. Many medical studies have demonstrated the prevalence of urinary tract infection in association with catheter drainage. A catheter cannot be passed with complete sterility because of the bacteria which normally resides within the distal urethra. It has been noted that two to three percent of patients will develop urinary tract infections after a single catherization. If the catheter remains indwelling, this figure rises rapidly with each passing day. Studies have shown that, after four to seven days, significant bacilluria may be found in 95% of patients with indwelling catheters.
Many attempts have been made to improve these statistics and great ingenuity has been expended in the design of catheters, drainage tubing, and collection bags in an effort to minimize the chances of infection. Measures such as careful techniques in catheter insertion, strict maintenance of a closed drainage system, and applications of topical antibiotic ointment to the urethral meatus have all been of some help in minimizing infection. Opinions vary on the use of prophylactic antibiotics such as sulfonamides or urinary anticeptic agents, such as nitrofurantoin, since no clinical study has conclusively demonstrated their advantage.
It is generally recognized that it is safest to utilize a completely closed system and to have the catheter, drainage tubing, and collection bag in continuity at all times. Unfortunately, it has been necessary to break or enter this closed system to perform regular irrigations and to collect urine specimens for urinalysis.
The single most effective method shown to minimize the infection problems in patients with indwelling catheters is the use of continuous bladder irrigation with a solution of antibiotics. Therefore, the use of a three-way self-retaining catheter is preferred. It has been shown that if a threeway irrigating system is introduced in a rigidly aseptic manner and the tubing is not disconnected to obtain a urine culture, urine can remain sterile at least up to ten days, and in some patients up to twenty days.